Process of producing a composite mold having cooling pipes embedded therein

ABSTRACT

Producing a mould by spraying a metal shell around a model, attaching pipes to the shell with a metal filled epoxy resin and subsequently backing the shell with a reinforcing material to enable the shell to be used in moulding, the method of attaching the pipes being such that no air pockets are formed in the region of the underside of the pipes adjacent the shell after the reinforcing material has been applied.

lite States Garner et a1. Jan. 8, 1974 [54] PROCESS OF PRODUCING ACOMPOSITE 2,317,597 4/1943 Ford et a1. 425/407 MOLD HAVING COOLING PIPES3,101,065 8/1963 Kalis .1 264/225 UX 3,424,635 1/1969 Grandinettic1211". 204/6 X EMBEDDED THEREIN 3,690,103 9/1972 Dederra et a1 204/9 X[75] Inventors: Paul Johnson Garner, Thorp Bay; 1,83 ,763 2/1931Bonsieur 1 204/6 X Thomas Robert Stephen Collins, 3,077,647 2/1963Kugler 174/19 1,357,343 11/1920 Novotny 1 249 80 X Letchworth, both ofEngland 2,793,177 5/1957 Fourier 204/20 X [73] Assignee: ImperialChemical Industries 3,498,371 3/1970 Zygiel 29/D1G. 1

Limited, London, England [22] Filed: 1972 Primary Examiner-Richard J.Herbst [21] Appl. No; 246,926 Assistant Examiner-D. C. Reiley, Ill

1 tt h b C Related US. Application Data A Omey Cus man Dar y & ushman[63] Continuation-impart of Ser. No. 885,172, Dec. 15,

1969, abandoned.

[57] ABSTRACT [52] 11.8. C1 249/80, 29/5272, 29/DIG. 39,

204/33 425/1316 30 Producing a mould by spraying a metal shell around a[51] Int. Cl. B29; 1/02 m del, attaching pipes to the shell with a metalfilled [58] Field Of Search 204/6, 9, 15, 20, epoxy resin andsubsequently backing the shell with a 204/38 33 19, reinforcing materialto enable the shell to be used in 5273,1316- moulding, the method ofattaching the pipes being 425/D1G. 30; 9/ such that no air pockets areformed in the region of the underside of the pipes adjacent the shellafter the [56] R fer n es Cit reinforcing material has been applied.

UNITED STATES PATENTS 1,935,916 11/1933 Ragsdale 164/46 X 38 Claims, 5Drawing Figures PATENTEDJAN 81114 3,784,152

sum e012 1 PROCESS OF PRODUCING A COMPOSITE MOLD HAVING COOLING PIPESEMBEDDED THEREIN This application is a continuation-in-part applicationof our U.S. Pat. application Ser. No. 885 172 filed Dec. 15, 1969, nowabandoned. The present invention relates to a process for the productionof moulds and to the moulds so produced. In particular the presentinvention relates to moulds for the production of articles fromthermoplastic materials, especially moulds suitable for injectionmoulding.

According to the present invention we provide a process for makingmoulds or mould halves comprising a) forming a shell of metal around amodel of the article to be moulded, b) adhering heating or cooling pipesto the metal shell using a metal filled epoxy resin as adhesive bypressing each pipe along its length into a layer of uncured metal filledepoxy resin deposited on at least the portion of said shell to whichsaid each pipe is applied and building up a wall of uncured metal filledepoxy resin against each side of each pipe, and applying to said shell areinforcing material to form a reinforcing backing on said shell withsaid pipes and metal filled epoxy resin encased in the reinforcingbacking (except at the ends of the pipes which are exposed) with theexclusion of air pockets adjacent the metal shell.

We prefer that the shell is at least l/l6 inch thick.

The present invention also provides moulds whenever made by thisprocess.

Our invention is particularly suitable for the production of mouldswhich are used in injection moulding. These moulds are generally knownas split moulds and are made in two halves which may be made separatelyby the process of the present invention and then located together.Alternatively one mould half may be made by the process of thisinvention, a model of the article to be moulded placed in the first halfand the metal shell of the other half formed around the model preferablyby metal spraying. It is then necessary to back the two mould halves andensure that they are in register with each other when mounted in thebacking material.

The model of the article to be moulded may be made in any requiredmanner and may be of any suitable material providing it is not adverselyaffected during the steps of the present invention. The model may bemade of wood, metal, plaster, synthetic thermoplastic, thermosettingresins, rubber especially silicone rubber, wax, plasticine, clay orglass reinforced polyester resin. We prefer that the model be mounted ona wood or metal base which has angled edges which provides means ofkeying the sprayed'metal coating around the model, as is described inour U.S. Pat. No. 3 638 299. The model itself should preferably containcooling pipes which should be fixed as closev to the surface to besprayed as possible. When the metal shell is produced by flame sprayingwe prefer that the model is sprayed with a water soluble release agentsuch as polyvinyl alcohol before spraying with metal. The release agentallows the metal shell to be parted readily from the model when immersedin water and also assists in the satisfactory laying down of the initialcoating of the sprayed metal. A

The metal shell may be formed around the model by electro-deposition,casting of metal, from sheet metal or by metal spraying. Any metal fromwhich a shell can be formed around the model may be used but we preferthat if the shell is formed by flame spraying it is of zinc. Lowshrinkage alloys particularly alloys of bismuth and tin are suitable forcompressed air spraying. These techniques provide a true reproduction ofthe model surface. A flame sprayed shell can be entirely of zinc or aminimum thickness of 0.050 inch of zinc backed by a low carbon steel,copper or aluminum. If metal spraying techniques are used aluminum isanother particularly suitable material as it is lighter, has lesstendency to crack and is readily sprayed at a high rate, i.e., metaldeposited per minute. A metal thickness of between one-sixteenth inchand one-quarter inch is preferred in the process of this invention.

After the production of the metal shell, pipes, preferably of copper,should be attached to the back of the metal shell, so that they followthe contours of the shell in a predetermined cooling or heating plan.The outer diameter of such pipes is usually within the range onequarterinch to three-eighths inch. We have found that if the pipes are fixed tothe metal shell the mould can be kept effectively cool during injectionmoulding cycles as the metal filled epoxy resin allows particularly goodheat exchange between the mould walls and a coolant flowing in thepipes. In an alternative embodiment the pipes can be attached to themetal shell with a metal filled epoxy resin and then more firmly adheredto the shell by further metal spraying to cover the pipes. This furthermetal layer also provides more reinforcement to the intially formedshell. If desired thermocouples may be stuck on to the metal shell withepoxy resin and this has the distinct advantage that they are in closeproximity of the mould face. The metal shell should now be backed with areinforcing material to enable it to be used in moulding operations.

It is essential in our process to attach the heating or cooling pipes tothe formed metal shell in such a way that voids (i.e., pockets of air)are not formed in the re gion of the underside of the pipes when theshell is subsequently backed with a reinforcing material. The presenceof such air pockets must always be avoided because the shell of thefinished mould will cave into the pockets when the mould is used in aninjection moulding cycle, owing to the extremely high pressuresgenerated inside the mould in such a process. Even in lower pressuremoulding processes such as blow moulding, there would always be thedanger of the shell collapsing into the air pockets. In addition, thepresence of air pockets may deleteriously affect the transfer of heat toor from the medium flowing in the pipes. Thus the simple and knownprocess of attaching a pipe comprising laying the pipe onto a flatsurface of the formed shell and merely spraying more metal over the pipeto stick it to the shell is unsuitable because such a process invariablyresults in the formation of air pockets between the shell and theunderside of the pipes.

The process of the present invention avoids the formation of air pocketsdue to the particular method used for attaching the pipes to the metalshell. in this method, the pipe is first contoured if necessary so thatit complies closely with the shape of the part of the model to which itis to be attached. Of course, if the part of the model to which the pipeis to be attached is flat, and the pipe itself is straight, thencontouring will not be necessary. A layer of uncured epoxy resin,preferably a strip of said resin, is then deposited along the part ofthe model to which the pipe is to be attached and the pipe pressed intothis uncured layer, which has the consistency of putty. It is preferableto press the pipe into the strip until it contacts the formed metalshell in order to achieve the best possible heat transfercharacteristics in the finished mould. A wall of the uncured epoxy resinis then built up against each side of the pipe. This may be achievedsimply by pressing the pipe deeply into the epoxide layer (if the layeris deep enough) so that the resin flows up and around each side of thepipe or (as is more usual) by carefully applying fresh quantities ofresin along each side of the pipe. if desired, the walls may be built upso that they meet, wherein the pipe is completely encased in the epoxyresin.

The above procedure is repeated or carried out contemporaneously foreach pipe which is to be attached to the metal shell. [t is preferablein our process to deposit a number of layers of the uncured epoxy resinin the form of strips onto said shell, each strip corresponding to apipe which is to be attached to the shell. However, it is within thescope of our invention for one deposited layer to serve for more thanone pipe which is attached to the shell or even for all the pipes to beattached.

After attaching each pipe and after allowing the epoxy resin to hardento a sufficient extent, and preferably after allowing it to becompletely cured, the shell is backed with at least one reinforcinglayer so that the pipes and epoxy resin are encased whilst leaving theirends exposed. Due to the build up of epoxy resin round the pipes, voidformation adjacent the shell may easily be prevented when applying thereinforcing backing.

As mentioned hereinbefore, thermocouples may also be attached to themetal shell at the same time as the pipes are attached. The method ofattachement may, if desired, be exactly analogous to that of theattachment of the pipes. However, it is usually not necessary to buildup a wall of epoxy resin against each side of the part of thethermocouple wire which contacts the metal shell, and merely pressingthe contacting part of the thermocouple into a spot of such resindeposited on the shell usually suffices. This is because thethermocouple wires are of very much smaller diameter (normally less thanone-eighth inch and often about one-sixteenth inch) than the cooling orheating pipes and moreover usually only contact the shell over a veryshort length (e.g. over about one-eighth inch) whereas the cooling orheating pipes generally extend right across the mould. The problem ofavoiding air pockets when attaching thermocouples is therefore much lessofa difficulty and usually merely tacking the thermocouple into a spotof resin is sufficient to avoid the formation of such pockets in thefinished mould.

The nature of the reinforcing material depends upon the use to which themould is to be put. The degree of reinforcing required depends upon themoulding operation. For example, if injection moulding techniques areused a high degree of reinforcement is required as the mould mustwithstand high pressures. In other moulding operations such as blowmoulding it is not essential that the mould be so strong. We have foundit particularly convenient to provide a first reinforcing layer aroundthe metal shell so that the shell may readily be removed from the modeland easily transported. This reinforced shell may then be backed with afurther reinforcing layer to enable it to be used in mouldingoperations. The first reinforcing layer may conveniently be formed bysurrounding the shell with the pipes adhering thereto with shuttering toform a cavity into which the first reinforcing material may be cast. Forexample wood shuttering may be mounted on the baseboard on which themodel stands so that the cooling pipes protrude through the shuttering.Steel tie bars may then be bent and fitted to criss-cross the formed boxand allowed to protrude each side. The rods serve two purposes, theyprovide means for transporting the backed metal shell and they also helpto tie the shell into the second reinforcing layer. If the metal shellhas been produced by spraying it is advisable to coat it with a waterrepellent paint before it is backed with the first reinforcing layer. Wehave found that concrete or aluminous cement are particularly suitablematerials to cast into the cavity formed by the shuttering to cover theshell and provide the first reinforcing layer. We prefer that the wholesystem be well vibrated to ensure there are no voids in the reinforcinglayer. When the backing material has cured the reinforced shell may beparted from the model. This reinforced shell will henceforth be referredto as the cavity insert.

The next step is to provide a second backing layer to the cavity insert.As previously stated the nature and extent of the backing depends on theuse for and size of the mould. For small moulds the metal shell withcooling pipes and thermocouples attached can conveniently be positionedin a wood or metal bolster frame which is then filled with the backingmaterial which is preferably concrete. The bolster would be assembled ona flat surface when casting the concrete around the cavity insert and weprefer that the surface is covered with a plastic film to give a goodfinish to the concrete and act as a release agent. A further advantageof providing the reinforcement in two stages is that any cracks whichmay appear in the outermost layer will not propagate into the otherlayers. If the moulds are to be used in injection moulding, we preferthat metal blocks be positioned at each corner of the bolster as isdescribed in our copending US. Pat. application No. 886,690, nowabandoned. The size of the metal blocks will depend on the mouldingmachine being used and the size of the moulding being produced.

If the process of the present invention is used to produce split mouldsfor injection moulding, the shell of the second mould half mayconveniently be prepared by inverting the first mould half and using thecavity as a spraying cradle to produce the metal shell for the othermould half. An angled beading is preferably fitted around the top of theinverted shell to provide a key for the sprayed metal as is described inour U.S. Pat. No. 3,638,299. Before any metal is sprayed into the cavitymaterial is deposited on the shell of first mould half to the requiredthickness to define the mould cavity.

Where the moulds are used for injection moulding a tapered hole calledthe sprue through which the polymer may be injected into the mould mustbe formed in the mould wall. Conveniently a metal block may beaccurately positioned on the cavity defining material before the metalis sprayed so that the block may be later drilled and reamed to providethe sprue. Metal may then be sprayed to the required thickness on to thewax around the metal block to form the shell for the second mould halfand the pipes already fitted to the cavity insert can now be used tocool the system when spraying. Alternatively the metal block may bepositioned behind the shell and a hole drilled through the two to formthe sprue; if this technique is adopted care must be taken to avoidcracking the shell.

Pipes and thermocouples should then be fitted to the second sprayedshell, in the same way as for the cavity insert. Thus the pipes mayconveniently be attached as hereinbefore described with a metal filledepoxy resin to ensure good heat transfer and if desired the adhesion maybe improved by spraying metal around the pipes. Wooden shutteringtogether with strengthening rods may then be fixed around the shell anda block of metal positioned to form an extension of the sprue blockpositioned on the wax. The block should extend beyond the level to whichthe reinforcement will be cast so that it may be drilled out to providethe sprue. Reinforcing material such as concrete or aluminous cement maythen be cast around the shell and allowed to cure so that it is selfsupporting. The concrete level should be below the top of the metalblock.

As stated above if the two mould halves are to be used to produce largemouldings in machines which exert a large force during moulding theymust be provided with a pressure resistant backing such as concrete andprovided with means whereby they may be located on a moulding machine.This may be conveniently achieved by mounting each of the mould halvesin a bolster which is then filled with reinforcing material, preferablyconcrete. The bolster should have walls of sufficient height to supportthe reinforcing material to the required depth, and the pipes should beof sufficient length that they extend to the outside of the bolster. Themeans whereby the moulds may be located on the moulding machineconveniently comprise metal blocks which may be located within thebolster, preferably at the corners, where they will be embedded in thereinforcing material, as is described in our copending U.S. Pat.application No. 886,690. Alternatively the blocks may be secured to theoutside of the bolster. It is of course, important that the two mouldhalves be correctly positioned with the bolsters with respect to eachother. We find that one mould half may conveniently be correctlypositioned within the bolster by providing supports in the bolster sothat when the insert rests on the supports it will be at the requiredheight within the bolster and filling the bolster to above the height ofthe supports with liquid settable reinforcing material. The mould halfmay then be lowered down into the reinforcing material and allowed tosettle until it comes to rest on the supports. The pipes andthermocouple leads being led through holes in the walls of the bolster.After the mould half has settled the bolster is finally filled withreinforcing material to surround the mould half.

An injection mould is generally positioned on a moulding machine by alocating ring which aligns the mould with the nozzle of the injectionunit. Conveniently the locating ring which is generally a metal block isaccurately positioned in the bolster so that it is held in the desiredposition by the concrete. In a preferred form the locating ring consistsof several steel rods fitted to the centre of the cylindrical block andextending radially therefrom so as to distribute any forces which may beexerted on the locating ring over a large area of concrete. The materialflowing through the injection nozzle of the moulding machine also exertsa substantial force on this area and thus it is preferred that the steelrods distribute these forces out to the bolts holding the mould on themachine platens.

It is finally necessary to mount the second mould half in itsreinforcing material and at the same time ensure that the two halvesmate together whilst providing a mould cavity of the required depth. Thesecond mould half may conveniently be located within a bolster which isthen filled with concrete so that the mould half is floating on theconcrete and is higher than its final required position. The first mouldhalf in its bolster is then lowered on to the second half so that themould insert in the second half is depressed to the required depth inthe concrete. The position of the second mould half will thus be definedby the position of the first mould half in its bolster. In a preferredmethod the two mould halves are located in the correct position withrespect to each other by means of the metal blocks provided in thecorners of the bolsters as is described in our copending U.S. Pat.application No. 886690, the blocks in one mould half being provided withdowels and the blocks in the other mould half with holes to receive thedowels so that when the dowels lock with the holes the two mould halvesare correctly positioned. Alternatively the blocks on one mould half maybe provided with guide plates within which the dowels of the other mouldhalf slide to ensure that the blocks contact when the mould closes.

The second mould half settles down in the concrete to the required depthand the concrete allowed to set. Finally, the metal blocks defining theline of the sprue must be drilled out to form the channel along whichmaterial may be injected into the mould and the mould mounted on themoulding machine.

The present invention is illustrated but in no way limited by referenceto the accompanying drawings in which FIG. 1 illustrates the model whichis used in the pro duction of the cavity insert.

FIG. 2 illustrates the model coated with a metal shell which is providedwith a rigid backing material.

FIG. 3 illustrates the mould half shown in FIG. 2 removed from the modeland inverted.

FIG. 4 illustrates the method of preparing the mould half illustrated inFIG. 3 as a model for the production of the other mould half.

FIG. 5 illustrates the formation of the other mould half.

With respect to FIG. 1 the model l is mounted on a wooden base board 2which has an angled edge 3 which will key the metal shell to the model.Cooling pipes 4 are provided at the back of the model to keep thesurface of the model cold during spraying and thus enhance the settingof the sprayed metal coating. As is illustrated in FIG. 2 the model isfirst spray coated with a layer of metal 5 to which are secured pipes 6by the method hereinbefore described and thermocouples 7 which have beensecured by tacking them to spots of resin deposited on the shell. Thesprayed model is then surrounded by shuttering 8 through which the endsof the pipes and the thermocouples extend. Metal keying rods 9 are bentto conform to the shape of the model within the shuttering so that whenthe aluminous cement 10 has set the mould half may be removed from themodel and inverted as is shown in FIG. 3 where one may see the mouldcavity 11.

The cavity insert illustrated in FIG. 3 is then used as the model forthe production of the other mould half as is shown in FIG. 4. Thesurface 11 of the cavity insert is first coated with a layer of wax 112to the thickness required for the mould cavity. A metal block 13 is thenpositioned on top of the wax in the position where the sprue is to beformed in the mould. The wax coated mould half is then sprayed with ametal layer 14 to form the other mould half as is illustrated in FlG.thermocouples 16 and pipes are then secured to the back of the metalshell by a metal filled epoxy resin adhesive in the same manner as thoseon the cavity insert. A metal block 17 is also provided behind the block13, shuttering l9 placed around the edges of the sprayed metal shell andaluminous cement 18 cast around to back the shell while leaving the endof the metal block 17 exposed. The second mould half may then be removedfrom the first half and the two mould halves together with thethermocouples and cooling pipes firmly adhered thereto may be mounted inrigid reinforcement such as concrete ready for use on an injectionmoulding machine.

We claim:

1. A process for making moulds or mould halves comprising a) forming ashell of metal around a model of the article to be moulded, b) adheringheating or cooling pipes to the metal shell using a metal filled epoxyresin as adhesive by pressing each pipe along its length into a layer ofuncured metal filled epoxy resin deposited on at least the portion ofsaid shell to which said each pipe is applied and building up a wall ofuncured metal filled epoxy resin against each side of said each pipe,and c) applying to said shell a reinforcing material to form areinforcing backing on said shell and said pipes with said pipes andmetal filled epoxy resin encased in the reinforcing backing (except atthe ends of the pipes which are exposed) with the exclusion of airpockets adjacent the metal shell.

2. A process according to claim 1 wherein said layer of uncured metalfilled epoxy resin is deposited as a strip onto said shell.

3. A process according to claim 1 wherein said each pipe is pressed intothe deposited layer of epoxy resin until it contacts the metal shell.

4. A process according to claim 1 in which the metal shell is formed toa thickness of at least one-sixteenth inch.

5. A process according to claim 1 in which before formation of the shellthe model is sprayed with a water soluble release agent.

6. A process according to claim 1 in which the metal shell is formed bymetal spraying.

7. A process according to claim 1 in which the metal shell is formed byelectrodeposition.

8. A process according to claim 1 in which the metal shell is made byflame spraying and is entirely of zinc.

9. A process according to claim 1 in which the metal shell is made bycompressed air spraying and is of an alloy of bismuth and tin.

10. A process according to claim 1 in which the metal shell consists ofa layer of zinc of minimum thickness 0.05 inch adjacent the model backedby a low carbon steel, copper or aluminum.

11. A process according to claim 1 in which the metal shell is about Ainch thick.

12. A process according to claim 1 in which the pipes are of copper.

13. A process according to claim 1 in which the pipes are stuck to themetal shell with a metal filled epoxy resin and a further metal coatingis then sprayed over the pipes to enhance the adhesion and heat transferbetween the pipes and the shell and to provide at least part of thereinforcing backing.

14. A process according to claim 1 in which thermocouples are alsomounted on the metal shell.

15. A process according to claim 13 in which the thermocouples are stuckto the metal shell with a metal filled epoxy resin.

16. A process according to claim 1 in which the metal shell is backedwith a first reinforcing layer before being removed from the model.

17. A process according to claim 15 in which the shell backed by thereinforcing layer is subsequently reinforced with a second layer.

18. A process for making moulds or mould halves for injection mouldingprocesses comprising forming a shell of metal around a model of thearticle to be moulded, adhering heating or cooling pipes to the metalshell using a metal filled epoxy resin as adhesive and backing saidshell to provide reinforcement to the shell and to encase the pipeswhilst leaving their ends exposed.

19. A process according to claim 18 in which the metal shell is formedto a thickness of at least onesixteenth inch.

20. A process according to claim 18 in which before formation of theshell the model is sprayed with a water soluble release agent.

21. A process according to claim 18 in which the metal shell is formedby metal spraying.

22. A process according to claim 18 in which the metal shell is formedby electrodeposition.

23. A process according to claim 18 in which the metal shell is made byflame spraying and is entirely of zinc.

24. A process according to claim 18 in which the metal shell is made bycompressed air spraying and is of an alloy of bismuth and tin.

25. A process according to claim 18 in which the metal shell consists ofa layer of zinc of minimum thickness 0.05 inch adjacent the model backedby a low carbon steel, copper or aluminium.

26. A process according to claim 18 in which the metal shell is about Ainch thick.

27. A process according to claim 18 in which the pipes are of copper.

28. A process according to claim 18 in which the pipes are stuck to themetal shell with a metal filled epoxy resin and a further metal coatingis then sprayed over the pipes to enhance the adhesion and heat transferbetween the pipes and the shell.

29. A process according to claim 18 in which thermo couples are alsomounted on the metal shell.

30. A process according to claim 29 in which the thermocouples are stuckto the metal shell with a metal filled epoxy resin.

31. A process according to claim 18 in which the metal shell is backedwith a first reinforcing layer before being removed from the model.

32. A process according to claim 31 in which the shell backed by thereinforcing layer is subsequently reinforced with a second layer.

33. A mould comprising a metal shell defining a moulding surface withcooling pipes stuck to the reverse side thereof by means of a metalfilled epoxy resin and backed with a reinforcing material which encasesthe cooling pipes while leaving their ends exposed.

moulding side thereof by means of a metal filled epoxy resin and backedwith a reinforcing material which encases the cooling pipes with theexclusion of air pockets adjacent the metal shell while leaving theirends exposed.

38. A mould according to claim 37 in which the reinforcing materialcomprises a first layer to render the shell self-supporting and a secondlayer to enable the mould to withstand moulding pressures.

UNITED STATES PATE T OFFICEJ a, CERTIFICATE OF CORRECTION Patent No.3,784,152 Dated January 8, v1974 Inventor) PAUL JOHNSON GARNER ET AL.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Please add the following to the front page format after the serialnumber:

[30] Foreign Application Priority Data December 30, 1968 Great Britain61659/68 This certificate supersedes Certificate of Correction issuedSeptember 17, 197% Zigneci and sealed this 8th day of April 1975.

it t e S t C I'EARSEZALL. DANE; TL-TE; 3 2:51.493 Commissioner ofPatents ttesttng Cfficer and Trademarks FORM FO-IOSO (10-69) UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION! Patent No. 3,784,152Dated January 8, 1974 lhventofls) PAUL JOHNSON GARNER and THOMAS ROBERTSTEPHEN COLLINS It is certified that error appears in theabove-identified patent l and that said Letters Patent are herebycorrected as shown below:

On the face of the Patent, please make the following changes:

After [75] Inventors: Paul Johnson .Garner, change "Thorp" to -ThorpeUnder "[21] ad d this paragraph: [30] Foreign Application Priority DataI December 5Ol968 I Great Britain 885,172

Signed and sealed this 17th day of September 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM P0-1050H0-691' 'USCOMM DC 003764,

h u s, oovnnuzuv rnmrmc ornc: nn o.-aeo-ua

1. A process for making moulds or mould halves comprising a) forming ashell of metal around a model of the article to be moulded, b) adheringheating or cooling pipes to the metal shell using a metal filled epoxyresin as adhesive by pressing each pipe along its length into a layer ofuncured metal filled epoxy resin deposited on at least the portion ofsaid shell to which said each pipe is appliEd and building up a wall ofuncured metal filled epoxy resin against each side of said each pipe,and c) applying to said shell a reinforcing material to form areinforcing backing on said shell and said pipes with said pipes andmetal filled epoxy resin encased in the reinforcing backing (except atthe ends of the pipes which are exposed) with the exclusion of airpockets adjacent the metal shell.
 2. A process according to claim 1wherein said layer of uncured metal filled epoxy resin is deposited as astrip onto said shell.
 3. A process according to claim 1 wherein saideach pipe is pressed into the deposited layer of epoxy resin until itcontacts the metal shell.
 4. A process according to claim 1 in which themetal shell is formed to a thickness of at least one-sixteenth inch. 5.A process according to claim 1 in which before formation of the shellthe model is sprayed with a water soluble release agent.
 6. A processaccording to claim 1 in which the metal shell is formed by metalspraying.
 7. A process according to claim 1 in which the metal shell isformed by electrodeposition.
 8. A process according to claim 1 in whichthe metal shell is made by flame spraying and is entirely of zinc.
 9. Aprocess according to claim 1 in which the metal shell is made bycompressed air spraying and is of an alloy of bismuth and tin.
 10. Aprocess according to claim 1 in which the metal shell consists of alayer of zinc of minimum thickness 0.05 inch adjacent the model backedby a low carbon steel, copper or aluminum.
 11. A process according toclaim 1 in which the metal shell is about 1/4 inch thick.
 12. A processaccording to claim 1 in which the pipes are of copper.
 13. A processaccording to claim 1 in which the pipes are stuck to the metal shellwith a metal filled epoxy resin and a further metal coating is thensprayed over the pipes to enhance the adhesion and heat transfer betweenthe pipes and the shell and to provide at least part of the reinforcingbacking.
 14. A process according to claim 1 in which thermocouples arealso mounted on the metal shell.
 15. A process according to claim 13 inwhich the thermocouples are stuck to the metal shell with a metal filledepoxy resin.
 16. A process according to claim 1 in which the metal shellis backed with a first reinforcing layer before being removed from themodel.
 17. A process according to claim 15 in which the shell backed bythe reinforcing layer is subsequently reinforced with a second layer.18. A process for making moulds or mould halves for injection mouldingprocesses comprising forming a shell of metal around a model of thearticle to be moulded, adhering heating or cooling pipes to the metalshell using a metal filled epoxy resin as adhesive and backing saidshell to provide reinforcement to the shell and to encase the pipeswhilst leaving their ends exposed.
 19. A process according to claim 18in which the metal shell is formed to a thickness of at leastone-sixteenth inch.
 20. A process according to claim 18 in which beforeformation of the shell the model is sprayed with a water soluble releaseagent.
 21. A process according to claim 18 in which the metal shell isformed by metal spraying.
 22. A process according to claim 18 in whichthe metal shell is formed by electrodeposition.
 23. A process accordingto claim 18 in which the metal shell is made by flame spraying and isentirely of zinc.
 24. A process according to claim 18 in which the metalshell is made by compressed air spraying and is of an alloy of bismuthand tin.
 25. A process according to claim 18 in which the metal shellconsists of a layer of zinc of minimum thickness 0.05 inch adjacent themodel backed by a low carbon steel, copper or aluminium.
 26. A processaccording to claim 18 in which the metal shell is about 1/4 inch thick.27. A process according to claim 18 in which the pipes are of copper.28. A process according to claim 18 in which the piPes are stuck to themetal shell with a metal filled epoxy resin and a further metal coatingis then sprayed over the pipes to enhance the adhesion and heat transferbetween the pipes and the shell.
 29. A process according to claim 18 inwhich thermocouples are also mounted on the metal shell.
 30. A processaccording to claim 29 in which the thermocouples are stuck to the metalshell with a metal filled epoxy resin.
 31. A process according to claim18 in which the metal shell is backed with a first reinforcing layerbefore being removed from the model.
 32. A process according to claim 31in which the shell backed by the reinforcing layer is subsequentlyreinforced with a second layer.
 33. A mould comprising a metal shelldefining a moulding surface with cooling pipes stuck to the reverse sidethereof by means of a metal filled epoxy resin and backed with areinforcing material which encases the cooling pipes while leaving theirends exposed.
 34. A mould according to claim 33 in which the metal shellis at least 1/16 inch thick.
 35. A mould according to claim 33 in whichthe pipes are copper pipes.
 36. A mould according to claim 33 in whichthe reinforcing material consists of a first layer applied to render theshell self supporting and a second layer to enable the mould towithstand moulding pressures.
 37. A mould comprising a metal shelldefining a moulding surface with cooling pipes stuck to the non-mouldingside thereof by means of a metal filled epoxy resin and backed with areinforcing material which encases the cooling pipes with the exclusionof air pockets adjacent the metal shell while leaving their endsexposed.
 38. A mould according to claim 37 in which the reinforcingmaterial comprises a first layer to render the shell self-supporting anda second layer to enable the mould to withstand moulding pressures.